Impact acceleration recording device

ABSTRACT

A weight disc has a wedge-like perimeter and is held between and by the inner edges of thin annular plates of plastic material in coaxial laminated state, the outer edges of the plates being fixedly held by an outer case which is secured to an object subject to possible impact. The disc responds to such impact by shifting from its original position to an impact position, its wedge-like perimeter driving into and along the interfacial seam between the plates to deform the same apart. The distance of the shifting of the disc is measured and referred to previously obtained data to determine the acceleration due to impact.

I United States Patent [151 3 707 722 Itoh [451 Dec. 26, 1972 [54]IMPACT ACCELERATION RECORDING DEVICE Primary Examiner-Joseph W. Hartary[72] Inventor: Klzu Itoh, No. 14-30 Sakuragaoka Atmmey -Rchard Sughme atfiglggme, Setagaya-ku, Tokyo, [57] ABSTRACT A weight disc has awedge-like perimeter and is held [22] i 1971 between and by the inneredges of thin annular plates [21] Appl. No.: 186,751 of plastic materialin coaxial laminated state, the outer edges of the plates being fixedlyheld by an outer case which is secured to an object subject to possibleimg pact. The disc responds to such impact by shifting from its originalposition to an impact position, its [58] Field of Search ..346/7, 11.1,71212412391142? wedgwke perimeter driving into-and along the imp facialseam between theplates to deform the same apart. The distance of theshifting of the disc is mea- [56] Refacing Cited sured and referred topreviously obtained data to UNITED STATES PATENTS 7 determine theacceleration due to impact.

3,218,870 11/1965 Baker .346 X 10 Claims, 6 Drawing FiguresPATENTEDBEBZBIQYZ 3.707.722

SHEEI 2 OF 2 FIG. 3

FIG.5

WEIGHT DISK DISPLACEMENT [(mm) m V 20 4C 60 8 0 I60 MAxIMuM IMPACTACCELERATION (G) IMPACT ACCELERATION RECORDING DEVICE BACKGROUND OF THEINVENTION maximum impact acceleration in instances such as incidents ofdropping of packaged articles onto the ground orother structures andcollisionssuch as those of motor vehicles. However, the manufacture ofan accurate and reliable instrument of simple and inexpensiveorganization andinstallation which can satisfy this need has been diffcult, and no such known instrument has heretofore been successfullyproduced.

One reason for this difficulty is that the operation of detecting andrecording the maximum value together with its direction, of anacceleration which is produced in a very short time and undergoes acomplicated variation, itself, is extremely'difficult, Another reason isthat, ordinarily, measurements of impact acceleration are desired withrespect to a large number of articles, and the possibility of occurrenceof impact is' distributed over this large number of articles.Accordingly,,unless the impact detecting and recording instrument ordevice is made inexpensively and attached in or on each article, theimpact accelerations resulting from instances of dropping or ofcollision, which 1 occur accidently and relatively infrequently, cannotbe effectively detected and. recorded.

SUMMARY OF THE INVENTION It is an object of this invention to fulfil theaforementioned need by. providing an impact acceleration recordingdevice which is not accompanied by the above described difficulties.

-More specifically, an object of this invention is to provide aneffective impact acceleration recording device which: 7 I

l. is capable of detecting and recording the maximum acceleration intwo-dimensional directions of impact, that is, in any direction in asingle plane; I

2. is capable of effecting and preserving a recording ofa maximumacceleration within the range of from G to 100G, which is ordinarilyproblematic;

perimeter, at least two thin annular plates of plastic materialdisposedin mutually coaxial laminated state and having circular inner edgesclamping from opposite sides the wedge-like perimeter of the weightdis'cand thus holding the weight disc in an original position I coaxial withthe plates, and a case fixedly holding the 3. can, itself, be secured toan article in a very simple manner by means such as an adhesive;

4. has an extremely simple construction and organization which,moreover, requires no energy source such as a dry cell battery or aspring; and

5. can be produced on a quantity (mass) production scale to sell at alow price.

The ultimate object of the invention is to provide an impactacceleration recording device of the above stated character which, wheninstalled extensively in packages of goods and in vehicles and the like,will contribute substantially to the solving of questions and problemsrelating to mishandling of packages and to accidents in which vehiclesand the like are involved.

outer peripheral parts of the plates and enclosing the discand theplates, the weight disc responding to an impact acceleration componentimparted to the case in a direction parallel to the annular plates toshift from the original position to an indication position as itswedgelike perimeter forcibly advances into and along the inte'rfacialseam between the plates and thereby deforms the plates. apart, thedistance between the original and the indication positions beingindicative of themagnitude of the impact acceleration component.

The nature, principle, and utility of this invention will be moreclearly apparent from the following detailed description with respect toa preferred embodimcnt of'the invention when read in conjunction withtheaccompanying drawings, inwhich like parts are designated by likereference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a planar view showing o'neexample of an impact acceleration recording device according to thisinvention.

FIG. 2 is a sectional view taken along a plane Il-Il passing through thecenter of the device shown in FIG. 1 perpendicularly to the plane of thedevice, the device being shown in its as-installed state beforeoperation.

FIG. 3 is an enlarged fragmentary sectional view showing the partenclosed within the dotted-like circle III in FlG. 2

FIG. 4'is a central sectional view similar to FIG. '2, showing thedevice in a state after it has been subjected to an impact and hasrecorded the same.

FIG. 5 is a graph based on measured results for determining values ofmaximum impact acceleration from recorded indications (weight discdisplacements) of the device.

FIG. 6 is a perspective view showing the particular case where two ofthe impact acceleration recording devices of the invention are combinedand installed in a mutually perpendicular state for three-dimensionalmeasurement in two mutually perpendicular directions.

DETAILED DESCRIPTION Referring to the drawings, the example illustratedtherein of the impact acceleration recording device according to theinvention comprises, essentially, a circular weight disc 1 constitutingan inertia reactor and having a sharp wedge-like peripheral edge 2, aplurality of thin annular plates 3,3 made of a plastic material andclamping around their inner edge parts, the peripheral edge 2 of thedisc 1, thereby supporting and holding the disc 1, a transparentcylindrical case 4 accommodating the disc 1 and the annular plates 3,3and having a closed bottom and an open top, and a transparent .coverplate 5 covering and closing the open top of the case 4. The cover platehas inscribed on its outer surface an arrow mark 6 for indicating. aninstallation reference direction. I

The weight disc 1 has a peripheral flange, part of the shape, insectional configuration being in the form of two identical frustums of acone joined coaxially baseto-base and. a central cylindrical boss 9projecting outwardly somewhat from the outer truncated faces of thefrustums. The bases of the conical frustums form at their intersectionthe aforementioned sharp circular edge 2, whereby the disc 1 has a shapewith two wedgelike ends in sections taken in planes through the disccenterline.

For the thin annular plates 3,3 in the illustrated example, fourannealed aluminum plates in laminated, coaxial arrangement are used, twoplates being disposed above the edge 2 of the weight disc land other twoplates being disposed therebelow as viewed in FIG. 2. The case 4 andcover plate 5 are made of a transparent material such as glass or asynthetic resin. The case 4 has around its interior an annular shoulderor ledge 7 on which the outer' peripheral part of the stack of theannular plates 3,3 rests and it held thereagainst by a spacer ring 8held in turn by the cover plate 5.

The weight disc is further provided through its boss 9 with an axialhole 10, in which are placed a spring '12 and steel balls 11 and 13abuttingly in contact with opposite ends of the spring 12, which therebyurges the steel balls 1 1 and 13 outward and against the inner surfacesof the case 4 and the cover plate 5, respectively. For recording, theseinner surfaces are coated beforehand with an inscribable material suchas layers of paint 14 and 1S, forexample.

The operation of the impact acceleration recording device of the abovedescribed organization according to this invention will now be describedwith respect to an example of its application for determining themaximum impact acceleration occurring in a collision'of a motor vehicle.

First, the device of this invention is secured by means such as anadhesive to a structural member near the central part of the vehiclenear its floor board, the reference direction arrow mark 6 on thecoverplate 5 being aligned with the direction of travel of the vehicle.

If this vehicle should collide with some object in an unforeseenaccident (or intentionally in a collision experiment), the weight disc 1initially at the center of the device will function as an inertiareactor with respect to the collision impact and will be propelled inthe direction of travel of the vehicle. Consequently, the sharpperipheral edge 2 of the weight disc] will drive forcibly into and alonginterfacial seam between the annular plates 3,3 on opposite sidesthereof, which plates are thereby forced apart and plastically deflectas indicated in FIG. 4 as the disc 1 advances into the interfacial scam.I

The weight disc I thus advances through a distance I from its originalcentral position 0 in the direction of travel of the vehicle, that is,opposite the direction of impact imparted to the vehicle, and stops.This distance I, which is a function of the maximum impact acceleration,can be measured directly after the collision. This measured distance Iis used in conjunction with a previously prepared graph as shown in FIG.5, indicating the relationship between the weight disc displacement, l,and maximum impact acceleration, to determine the maximum impactacceleration of the collision.

While the displacement distance I can bemeasured directly as describedabove in instances of single collisions, there may be instances wheresecondary and even further collisions occur subsequently to move theweight disc 1 to a position other than the position corresponding to'the distance I and the maximum impact acceleration.

In such cases, the provision of the steel balls 11 and 13 disposedwithin the weight disc l and urged outward by the spring 12 against thecase 4 and cover plate 5 affords great convenience in that these steelballs operate as styluses to inscribe a trace 16, directly indicatingthe path of movement of the weight disc, in the paint layers 14 and 15on the inner surfaces and thereby to leave a record of this movement.Accordingly, this record can be observed through the transparent caseand cover plate 4 and 5, and the distance I from the original discposition 0 to the outer end 17 of the trace 16 can be measured from 'theoutside without the necessity of opening the cover plate 5.

' In the case where the impact acceleration acts in a direction which'is inclined relative to the planar direction of the device, one of thesteel balls 11 and 13 may temporarilyseparate from the inner surfaceofthe case 4 or cover plate 5, in which case the above mentioned'recordis not completely inscribed and is thereby interrupted. However, theother steel ball, without fail, is pressed firmly with increased forceagainst its corresponding recording surface, whereby there'can never bean instance wherein-the trace 16 is not inscribed on either of the innersurfaces of the case 4 and cover plate 5. That is, the shift distance Iof the weight disc 1 can be measured from the inscribed trace 16remaining on at least one of the ink-coated surfaces and, moreover, canbe reproduced.

Another important feature of this invention is that the inscribed trace16 indicates the direction of the impact acceleration. Therefore, if thetrace 16 is found to be substantially in the direction of travel of thevehicle after a collision, that is, in the direction of arrow mark 6, itmay be surmised that the vehicle collided head on with the other object.On the other hand, if the trace 16 is found to be in the oppositedirection, it may be surmised that the vehicle was bumped from the rear.

Furthermore, if the position of the weight disc or the direction of thetrace 16 is oblique or inclined relative to the front-to-rear directionof the vehicle, this will mean that impact was imparted obliquely to thevehicle. That is, the angle between the front-to-rear axis of the deviceand the trace 16 will indicate the angle between the front-toreardirection of the vehicle and the collision direction,

As stated hereinbefore, a graph such as that shown in FIG. 5 isnecessary for determining maximum impact accelerations from measuredvalues of the distance I. This graph can be drawn to show averagemeasured values indicating the relationship between the distance I andthe maximum impact acceleration as determined from the results ofexperiments carried out with a separate impact tester and severaldevices of the same specification as a device involved in a collision.It has been found that remarkably consistant and accurate results can beobtained as indicated in H0. 5, which is based on actual experimentalresults. 1

Specification values such as the weight of the weight disc 1 and thematerial, thickness, and number of the plastic annular plates areselected in accordance with the required range of impact acceleration. I

Although not'shown in the drawings, concentric circles radially spacedone millimeter apart and having their common center at the center of thedevice can be inscribed on the case 4 and cover plate 5 for simpledirect reading of the distance 1. Furthermore, in the case wheremeasurement of impact acceleration due to atwo-dimensional collision isinsufficient, two of the devices of this invention can be used in acombined arrangement as. indicated in FIG. 6, in which the two deviceslie in mutually perpendicular planes. A collision resulting inthree-dimensional impact acceleration can then be recorded. v Theresults of experiments with prototypes of-the impact acceleration,recording device of this invention indicate that, with the use ofadevice in which two annu-. lar plates 3,3 made of annealed aluminum of0.l5?mm, thickness and wieght disc 1 of IO-gram weight are used, theweightdisc 1 shifts 1 mm per impact acceleration of 100, and a maximumacceleration of 800 can be measured corresponding to a displacement of 8mm of the weight disc with an accuracy of 1 56. Each recording deviceused in these experiments had an overall diameter of 52mm, an overallthickness of 10 mm, and a total weight of 25 grams. 7

It wasfound further that there is no displacement whatsoever of theweight disc with respect to vibration 6 acceleration component impartedto the case in a direction parallelto the plates to shift from saidoriginal I position to an indication position displaced therefrom as theperipheral edge thereof forceably advances into and along saidinterfacial seam, deforming the plates apart with thedistance betweenthe original and displaced positions being indicative of the magnitudeof the im act acceleration component.

orimpact of a magnitude of 100 or less because of friction of theannular aluminum plates. Accordingly, the zero point or original settingof the device cannot be disturbed by ordinary handling andtransportation.

While this invention has been described above with respect to onespecific example thereof, it will be apparent that various modificationscan be made therein. For example, while the case 4 and cover plate 5 areof circular shape in planar view in the above described example, theycan be made to have a square peripheral shape.

Thus, as is apparent from the foregoing disclosure, the impactacceleration recording device of this invention fully achieves theaforestated objects thereof.

What is claimed is:

1. An impact acceleration recording device comprising a circular weightdisc constituting an inertia reactor and having a sharp peripheral edgeof wedge shape in section passing through the disc axis, at least twothin plates made of a plastic material and disposed with an interfacialseam therebetween, said plates clamping from opposite sides theperipheral edge of said weight disc and holding the weight disc in anoriginal position within the plates; and a case fixedly holding theouter edge portions of the plates and enclosing the plates and theweight disc, the weight disc responding to impact 2. e impactacceleration recording device according to claim 1, in which recordingmeans are provided for recording a trace of the path travelled by theweight disc.

3. The impact acceleration recording device according'to claim 2, inwhich the case further includes at least one transparent wall overlyingone of the plates, said one plate having an opening therein, the weightdisc being initially .centered within said opening, the inner surface ofsaid one wall being coated with an inscribable layer, and recordingmeans comprising said inscribable layer and stylus means mounted on theweight disc and in contact with said inscribable layer to' inscribe saidtrace of movement of said weight disc thereon.

4. The impact acceleration recording device according to claim. 1,further comprising a reference ing to claim 5, in which a total of fourannular plates are involved, two on each side of the weight disc.

7.The impact acceleration recording device according to claim 5, inwhich the annular plates are made of annelaed aluminum sheet material. I

8. The impact acceleration recording device according to claim 5, inwhich recording means are provided for recording a trace of the pathtravelled by the weight disc.

9. The impact acceleration recording device according to claim 8, inwhich the case is provided with at least onetransparent wall extendingparallel to the weight disc and overlying one of said annular plates,the inner surface of said transparent wall being coated with aninscribable layer and stylus means mounted on the weight disc and incontact with said inscribable layer to record the trace of movement ofsaid disc with respect to said two thin annular plates supporting thesame.

10. The impact acceleration recording device according to claim 9 inwhich an opening is provided in the center of said disc and a springbiased ball projects outwardly therefrom to form said stylus means.

106012 Ol8l

1. An impact acceleration recording device comprising a circular weightdisc constituting an inertia reactor and having a sharp peripheral edgeof wedge shape in section passing through the disc axis, at least twothin plates made of a plastic material and disposed with an interfacialseam therebetween, said plates clamping from opposite sides theperipheral edge of said weight disc and holding the weight disc in anoriginal position within the plates; and a case fixedly holding theouter edge portions of the plates and enclosing the plates and theweight disc, the weight disc responding to impact acceleration componentimparted to the case in a direction parallel to the plates to shift fromsaid original position to an indication position displaced therefrom asthe peripheral edge thereof forceably advances into and along saidinterfacial seam, deforming the plates apart with the distance betweenthe original and displaced positions being indicative of the magnitudeof the impact acceleration component.
 2. The impact accelerationrecording device according to claim 1, in which recording means areprovided for recording a trace of the path travelled by the weight disc.3. The impact acceleration recording device according to claim 2, inwhich the case further includes at least one transparent wall overlyingone of the plates, said one plate having an opening therein, the weightdisc being initially centered within said opening, the inner surface ofsaid one wall being coated with an inscribable layer, and recordingmeans comprising said inscribable layer and stylus means mounted on theweight disc and in contact with said inscribable layer to inscribe saidtrace of movement of said weight disc thereon.
 4. The impactacceleration recording device according to claim 1, further comprising areference directional mark provided on the outer surface of the case forindicating the installed orientation of the device.
 5. The impactacceleration recording device as claimed in claim 1, wherein said platesare annular in form and are disposed in mutually coaxial laminated statewith the circular inner edges of said plates clamping the peripheraledge of the weight disc from the opposite side.
 6. The impactacceleration recording device according to claim 5, in which a total offour annular plates are involved, two on each side of the weight disc.7. The impact acceleration recording device according to claim 5, inwhich the annular plates are made of annelaed aluminum sheet material.8. The impact acceleration recording device according to claim 5, inwhich recording means are provided for recording a trace of the pathtravelled by the weight disc.
 9. The impact acceleration recordingdevice according to claim 8, in which the case is provided with at leastone transparent wall extending parallel to the weight disc and overlyingone of said annular plates, the inner surface of said transparent wallbeing coated with an inscribable layer and stylus means mounted on theweight disc and in contact with said inscribable layer to record thetrace of movement of said disc with respect to said two thin annularplates supporting the same.
 10. The impact acceleration recording deviceaccording to claim 9 in which an opening is provided in the center ofsaid disc and a spring biased ball projects outwardly therefrom to formsaid stylus Means.